1. Field of the Invention
The present invention relates to a member for guiding the harness cords of a weaving loom harness of Jacquard type. It also relates to a Jacquard harness and to a shed-forming device incorporating such a guiding member. Finally, the invention relates to a method for guiding the harness cords of such a harness.
2. Description of the Related Art
In the domain of weaving looms of Jacquard type, it is known to guide the harness cords constituting the harness thanks to a perforated board disposed in the vicinity of the Jacquard system, i.e. in the upper part of the superstructure of the loom, and thanks to a comber board installed above the shed-formation zone, these boards making it possible to distribute the harness cords in space. The harness cords thus follow curved paths defined by the holes that they traverse, respectively, in the perforated board and in the comber board. Taking into account the angles of these paths with respect to the vertical, frictions are generated at the level of these holes, which generates heating and premature wear of the harness cords. Such wear is accentuated by the pollution of the zone of contact between the harness cords and the edges of these holes. In effect, flock tends to be deposited on these guiding members and to penetrate between the harness cords and the edges of these holes.
It is a more particular object of the present invention to overcome these drawbacks by proposing a novel structure of guiding member which makes it possible to limit heating and wear of the cords.
To that end, the invention relates to a guiding member of the aforementioned type which is provided with holes for passage of the harness cords and which is characterized in that these holes are arranged in such a manner that at least one harness cord passes through two holes which communicate with at least one space adapted to be placed under excess pressure by a supply from a source of pressurized gas, these holes constituting orifices for exit of the gas with respect to the space.
With the invention, the substantially closed space or volume defined between two plates in which the holes are made serves as a distributor for the pressurized gas, for example air. xe2x80x9cExcess pressurexe2x80x9d is understood to mean that the pressure of the gas, in the volume defined between the afore-mentioned plates, is greater than ambient atmospheric pressure. The gas thus tends to escape through the orifices made in the plates. This gas sweeps over the harness cords which it cools, while it drives flock away from edges of the holes through which the cords pass. In other words, the circulation of the gas, which passes from the inside of the guiding member to the outside, cleans areas of contact between the harness cords and the plates, which makes it possible to eliminate or limit the abrasion of the harness cords. This circulation also induces cooling of these cords, which makes it possible to limit the losses of their technical characteristics which occur with the conventional devices. In this way, the life of the harness of a Jacquard loom equipped with a guiding member according to the invention is increased, while the speeds and the loads applied to this harness may be increased. In addition, the maintenance operations can be spaced out, including in the case of a loom working in a polluted atmosphere. Finally, the internal volume or space of the guiding member makes it possible to distribute the cooling/cleaning gas, with the result that all the harness cords are cooled and cleaned in substantially uniform manner.
According to advantageous but non-obligatory aspects of the invention, the guiding member incorporates one or more of the following characteristics:
the two holes are made in two plates separated by the aforementioned volume or space.
the holes provided, respectively, on a first and on a second plate are substantially aligned with respect to one another in a substantially vertical direction when the guiding member is mounted on a weaving loom.
at least one connection is provided, for connecting each internal volume or space of the guiding member to an outside source of gas under pressure; and
spacer elements are provided for separating the aforementioned plates, these spacers forming peripheral partitions defining each volume or space. In that case, the aforementioned connection is advantageously immobilized on and traverses one of these spacers.
According to a first advantageous embodiment of the invention, the guiding member forms a perforated board disposed in the vicinity of a Jacquard system for guiding the harness cords. According to another advantageous embodiment of the invention, this member forms a comber board.
The invention also relates to a Jacquard harness which comprises a guiding member as defined hereinabove. The life of such a harness is substantially increased with respect to those of the prior art.
The invention also relates to a shed-forming device of a weaving loom of the Jacquard type which comprises a guiding member as described hereinabove. Such a shed-forming device is easier to use and more economical than the known devices.
Finally, the invention relates to a method for guiding harness cords which may be carried out with a guiding member as described hereinabove. This method comprises steps consisting in causing the harness cords to pass through a guiding member provided with two plates in which holes are made for passage of these cords and between which a substantially closed volume is defined, and in supplying this volume with pressurized gas, with the result that the gas escapes from this volume through these holes.